The purpose of this research study is to evaluate the effect of AZD3199 on the electrical activity of the heart. The effect of AZD3199 will be compared to a licensed antibiotic (moxifloxacin). Moxifloxacin effects on the electrical activity of the heart are well known. Safety and tolerability of AZD3199 and how much AZD3199 enters the blood circulation will also be assessed.